1. Field of the Invention
The present invention generally relates to light-emitting diode (LED), and more particularly to an alternating-current (AC) LED lamp.
2. Description of Related Art
A light-emitting-diode (LED) lamp uses LEDs as a light source. The LED lamp has a longer lifetime and consumes less energy than a conventional fluorescent lamp, and is thus becoming more acceptable as a lighting device.
The LED is commonly driven by a direct-current (DC) power supply or an alternating-current (AC) to DC converter such as a switching power supply. However, the conversion efficiency of the conventional switching power supply is at best 90% and is oftentimes lower than that. Moreover, the conventional switching power supply is bulky due to its use of large capacitor and/or inductor.
In addition, the LED lamp is adapted to a specific AC power in a specific region or country. The voltage of the AC power varies in the range 100-240 volts, and the frequency of the AC power is either 50 Hz or 60 Hz. Accordingly, an LED lamp made for a region cannot be used in another region, without thorough reconstruction.
Another drawback of the conventional LED lamp is its susceptibility to power noise that will make the lamp flicker. The power noise may be reduced, however, at the cost of using more capacitors and/or inductors.
For the reason that the conventional LED lamp could not effectively and efficiently provide the purpose of lighting, a need has arisen to propose a novel LED lamp that has high power efficiency, lower volume, better adaptability to a variety of power voltages or improved immunity to power noise.